As a soft packaging material made of a plastic film, a bag body having self-standing properties, a so-called self-standing bag is known. As the self-standing bag, a self-standing bag formed in such a manner that side edges of two barrel members and side edges of a bottom member are heat-sealed together, and lower ends of two barrel members are heat-sealed over the entire circumference in a state in which the folded bottom member which forms a bottom portion sets a folding line upward and is inserted between the lower ends of two barrel members which form a barrel portion, can be mentioned. However, in the self-standing bag, a heat-sealed portion between the side edges of two barrel members formed on edges of the barrel portion may feel like a knife edge. For this reason, when the barrel portion of the self-standing bag is grasped using one's hand, there may be an uncomfortable feeling.
In Patent Document 1, to eliminate such uncomfortable feeling when the barrel portion is grasped using the hand, as shown in FIG. 23, a self-standing bag 101 that includes a barrel portion 110 with a flattened cylindrical shape which has a front surface portion 111 and a back surface portion 112 and in which creases are provided on both sides, and a bottom portion 120 which is provided on a lower end of the barrel portion 110 is shown.
The barrel portion 110 is formed in a flattened cylindrical shape by matching the side edges of two rectangular barrel members. That is to say, the barrel portion 110 with the flattened cylindrical shape that has the front surface portion 111 and the back surface portion 112 is formed by heat-sealing the side edges of the barrel portion 110 to form a back seal 113. The barrel member which forms the barrel portion 110 is configured such that an inner surface of the barrel portion 110 is made up of a sealant layer having heat-sealing properties and an outer surface of the barrel portion 110 is made up of a laminated film of basic material layers.
As shown in FIG. 24A, the bottom portion 120 is formed with a rectangular bottom member 120A in which the basic material layer without heat-sealing properties and the sealant layer with heat-sealing properties are laminated. As shown in FIG. 24A, side portions 121 and 122 of the bottom member 120A are folded along folding lines L121 and L122 so that the basic material layers of the side portions 121 and 122 and a basic material layer of a center portion 123 are in close contact. As shown in FIG. 24B and FIG. 24C, the bottom member 120A of which the side portions 121 and 122 are folded is further folded along a folding line L123 so that the side portions 121 and 122 are folded inside. At this time, a contact surface of a first side portion 121a and a second side portion 121b in the folded side portion 121 is made up of the sealant layer. In addition, a contact surface of a first side portion 122a and a second side portion 122b in the folded side portion 122 is made up of the sealant layer. In addition, a contact surface of the center portions 123 between the folded side portions 121 and 122 is made up of the basic material layer. As shown in FIG. 24C, facing surfaces of the first side portion 121a and the second side portion 121b in the folded side portion 121 are heat-sealed, and the facing surfaces of the first side portion 122a and the second side portion 122b in the folded side portion 122 are heat-sealed. Then, as shown in FIG. 24D, the bottom member 120A is formed in a pouch shape with a lower end 120c opened. The pouch-shaped bottom member 120A has an outer surface side made up of the sealant layer.
As shown in FIG. 23, the pouch-shaped bottom member 120A is arranged in the barrel portion 110 so that the lower end 120c of the bottom member 120A matches a lower end 110c of the barrel portion 110. Then, by heat-sealing the lower end 120c of the bottom member 120A and a lower end 110c of the barrel portion 110 at a heat-sealed portion HS101, the side edges 120a and 120b and the lower end 120c of the bottom member 120A are adhered to the inner surface of the barrel portion 110 to form the bottom portion 120.
The barrel portion 110 of the self-standing bag 101 is formed with one barrel member. Due to this, the heat-sealed portion which is formed by heat-sealing the side edges of the barrel member in edges 110a and 110b of the barrel portion 110 is not present. As a result, even when barrel portion 110 is grasped using the hand, any uncomfortable feeling is reduced.
As shown in FIG. 25, in the bottom portion 120 of the self-standing bag 101, the facing surfaces of the side portion 121 folded inside and the bottom portion 120 are not adhered by heat-sealing since the basic material layers contact each other. Therefore, the vicinity of the side edge 110a of the barrel portion 110 is spread, and a shape which takes on roundness is obtained. As a result, even when the vicinity of the bottom portion 120 of the barrel portion 110 is grasped using the hand, any uncomfortable feeling is reduced.
Since the shape which takes on roundness can be obtained in the side portion 122 like the side portion 121, any uncomfortable feeling is reduced.